1. Field of the Invention
This invention relates to the field of construction and formation of front loading magnetic disk memory cartridge packs used by computers.
2. Description of the Prior Art
Random access disk memories have been used extensively in data processing systems. Such disk memories employ a disk assembly of one or more magnetically coated disks which can be mounted on a drive unit for recording on and reproducing data from the surfaces of the disk or disks. A cartridge, an enclosure or a cover is provided for the disk assembly to facilitate handling and storage, and to protect the surface of the disks during installation and removal from the drive unit. The cartridge prevents human contact with the disk surfaces and seals the disk and disk assembly from airborne contaminants.
Such cartridges are constructed to allow the necessary connections to be made with the drive unit, including the introduction of one or more transducers into close proximity to the disk surface and the attachment of the disk assembly to a drive shaft for rotation of the disk assembly.
Previously, cartridges have been constructed having a removable base cover which can be detached when the base of the cartridge is attached to the drive unit. The base of the cartridge may be rotated by the drive unit with the disk assembly. Another type of cartridge is also known which encloses the disk assembly even when the disk assembly is attached to the drive unit. This type of cartridge is provided with an access door which opens automatically when the cartridge is installed in the drive unit to allow for the insertion of a transducer.
As data densities of cartridges have increased and transducers heads are positioned closer to the disk, system margins are reduced to the point where tolerances in micro-inches must be maintained. In order to maintain these tolerances in the field, the disk and hub within the plastic cartridge must be additionally protected from potential handling and contamination problems. This additional protection is provided by a base guard. The use of a base guard also allows storage of disk cartridges in a vertical position (as opposed to flat storage) without seriously increasing storage hazards.
A representative sample of a base guard is illustrated in U.S. Pat. No. 3,635,608 (element 4). Such a base guard is attached to the disk cartridge by means of magnets which act upon the metal hub of the cartridge to secure the base guard. Such a base guard thus requires at least two steps to make, namely: (1) formation of the plastic guard; and (2) attachment of magnets to the base guard. These prior art base guards cover substantially all of the base surfaces of the disk cartridges. However, most cartridges are constructed to have a recess in their top surface and an opposing complementary recess in the base to serve as a hand hold for the cartridges. Such base guards cover the recess and prevent the functioning of the recess usually provided in the base as a handhold. Other base guards are merely slightly oversized copies of the lower surface of the disk cartridge itself.
What is needed is a base guard, for computer disks cartridges, which is of unitary construction and does not require the fastening of magnets to the base guard to hold the base guard onto the cartridge. There is a further need for a base guard which does not cover the entire base of the cartridge, but rather covers all of the base except the cooperating handhold or recess in the base. In addition, it is desired that the base guard be sufficiently rigid to provide sufficient strength against impact from a direction parallel to the axis of the hub and that such base guard be formed so as to permit vertical, nested, registered and interlocked stacking of cartridges in order to minimize storage space requirements.